DOD Model:-

          The first layered protocol model we will study is the 4-layer DoD Model. This is the model originally designed for the Internet, and is important because all of the Internet’s core protocols adhere to it.

         The Department of Defense Four-Layer Model was developed in the 1970s for the DARPA Internetwork Project that eventually grew into the Internet. The core Internet protocols adhere to this model, although the OSI Seven Layer Model is justly preferred for new designs.